1. Field of the Invention
This invention relates to apparatus for detecting measuring and/or displaying differences from the desired ideal performance characteristics of a golf swing. The apparatus may be used to track the motion and orientation of the clubhead during the execution of a golf swing.
2. Description of the Prior Art
Several forms of such apparatus are known. In one known type of apparatus the position and orientation of the clubhead during a golf swing is sensed by an array of narrow beam electro-optical sensors. In a typical array, two parallel rows of closely spaced electro-optical sensors are mounted at ground level behind the initial tee position of a golf ball. The two rows of electro-optical sensors are perpendicular to the straight swing path that is the nominally correct, undeviated line of swing. One row of the electro-optical sensors is set slightly behind the tee position, and the other row of electro-optical sensors is set a further distance behind, the separation of the two rows being by some known distance. The clubhead swing trajectory starts from behind the tee position and, during a golf swing, an electrical signal change is generated in any given electro-optical sensor circuit when the clubhead passes vertically above the electro-optical sensor. By monitoring all of the electrical signals from the array, the position and inclination of the clubhead as it sweeps above each row can be computed. From this, the angle of swing, the skewness of the clubhead and its offset from centre can be computed. The speed of the clubhead, averaged across the sensor zones, can also be computed, this being proportional to the row separation and to the inverse of the time taken by the clubhead to traverse the two rows, assuming small swing angle deviations from the normal.
The above mentioned known apparatus suffers from the disadvantage that a large number of the electro-optical sensors is required because a large number of discrete points are monitored. This in turn leads to increased manufacturing costs and complexity of equipment.
Another type of apparatus depends upon magnetic sensors located in and around the notional impact area and upon their magnetic interaction with the metal of the club head, or in some cases with metal and magnetic inserts specially placed in the club head. Changes in the magnetic fields are picked up at the sensors and can be displayed digitally, or manifested as a diagnostic round or visual signal. Examples of such equipment are described in GB 2135199B, GB 2150841B, GB 2110939B, U.S. Pat. No. 4,844,469, U.S. Pat. No. 4,451,043, GB 2217995A and GB 2223952A.